<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<style>
  #neon-btn {
    display: flex;
    align-items: center;
    justify-content: space-around;
    height: 100vh;
    background: #031628; 
  }

  .btn {
    border: 1px solid;
    font-size: 14px;
    padding: 10px 20px;
    font-weight: 300;
    text-transform: uppercase;
    background-color: transparent;
  }

  .one {
    color: #4cc9f0;
  }

  .two {
    color: #f038ff; 
  }

  .three {
    color: #b9e769;
  }

  .btn:hover {
    color: white;
    border: 0;
  }

  .one:hover {
    background-color: #4cc9f0;
    box-shadow: 10px 10px 99px 6px rgba(76,201,240,1);
    -webkit-box-shadow: 10px 10px 99px 6px rgba(76,201,240,1);
    -moz-box-shadow: 10px 10px 99px 6px rgba(76,201,240,1);
  }

  .two:hover {
    background-color: #f038ff;
    box-shadow: 10px 10px 99px 6px rgba(240, 56, 255, 1);
    -webkit-box-shadow: 10px 10px 99px 6px rgba(240, 56, 255, 1);
    -moz-box-shadow: 10px 10px 99px 6px rgba(240, 56, 255, 1);
  }

  .three:hover {
    background-color: #b9e769;
    box-shadow: 10px 10px 99px 6px rgba(185, 231, 105, 1);
    -webkit-box-shadow: 10px 10px 99px 6px rgba(185, 231, 105, 1);
    -moz-box-shadow: 10px 10px 99px 6px rgba(185, 231, 105, 1);
  }

</style>
<body>
  <div id="neon-btn">
    <button class="btn one">Hover me</button>
    <button  class="btn two">Hover me</button>
    <button  class="btn three">Hover me</button>
  </div>
</body>
</html>